Hol Igor Notes On Ko

    Keywords: Ko
[Diagram]

Dango if Black connects, ending the ko

Ugly

[Diagram]

To end the ko, Black captures

Much better

Charles True, but it seems that WC is wasted here. Local tally and efficiency of shape are probably more important than thinking about dango shape, in these cases of ko.
Charles Yes, it's a good point, and sometimes this strategy is seen in pro games. If one player has many more large threats, say Black has five more, winning a ko will still leaves Black four more large threats and (depending on whether the ko result is thick or not) White may have gained none.
Charles I called this issue 'Addition Tally Principle' in my articles on Gobase. It's not a simple matter, but in general you could say that increasing the value of the ko is only correct for the player who will win it.
Bill: One of those complications Charles alludes to is the ko exchange. Upping the ante is OK, even if you lose the ko, if you get enough in exchange for it. Such situations are not all that uncommon.
Charles Actually, just saying 'increasing' could mean several things. In some cases a player ignores a ko threat to play another move near the ko, which makes finishing the ko more attractive for one side (like in the example at the top of the page). What is at risk in that case is that if the ko goes the other way, that play will be a wasted move, a bad trade for the ignored ko threat. And on the other hand some common local ko threats just make the number of points involved larger, without changing what I call the local tally.
Charles It is a proverb that 'adding one stone in a ladder can cost seven points'.

This is a copy of the living page "Hol Igor Notes On Ko" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.
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